Apparatus for generating high-frequency alternating currents.



PATENTED JUNE 18, 1907.

M. LEBLANG.

APPARATUS FOR GENERATING HIGH FREQUENCY ALTERNATING GURRENTS.

APPLIUATION FILED MAR.14. 1906.

3 SHEETSSHEET 1.

No 857.561. PATENTED JUNE 18 190?. M. LEBLANG,

APPARATUS FOR GENERATIIQG HIGE FREQUENCY ALTERNATING GURRENTS.

APPLIOATIOII FILED HAIL. 14. 190B.

' 3SHEBTSSHEET 2.

. Suvanl'ot 7 J Zm nae ll wu zzay, Witnesses;

auto-unw ry No. 857,561. PATENTED JUNE 18, 1907. Ml LEBLANG.

APPARATUS FOR GENERATING HIGH FREQUENCY ALTERNATING GURRENTS.

APPLICATION FILED MAR. 14. 1 906.

3 SHEETS-SHEET 3 UNITED STATES PATENT OFFICE.

MAURICE LEBLANC, OF PARIS, FRANCE, ASSIGNOR TO WESTINGHOUSE ELECTRIC &MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

Specification of Letters Patent.

Patented June 18, 1907.

Original application filed February 5, 1904, Serial No 192,227. Dividedand this application filed March 14, 1906.

Serial No. 306,033.

To all whom, it nutty concern:

Be it known that I, MAURICE LEBLANG, a citizen of the Republic ofFrance, and a resident of Paris, France, have invented a new and usefulApparatus for Generating High- Frequency Alternating Currents, of whichthe following is a specification.

In an application N 0. 183,246, heretofore filed by me, on Nov. 30,1903, I have delo scribed and claimed a means for producingunidirectional currents, which comprises a dynamo generating andalternating electromotive force having its maximum value of one signgreater than its maximum value of r 5 the opposite sign, and an electricexploder which is adjusted to establish an arc and to permit current topass only with the electro motive-force of that sign which has thegreater maximum value. The unidirectional current thus produced, may bemade continuous by means of a condenser in shunt of these parts.

In another application No. 183,247, heretofore filed by me, on Nov. 30,1903, I have shown a means for changing the continuous currents thusproduced into alternating cur rents traversing the primary coilof atransformer, which means consists, generally speaking, of a resonatorconnected to the line carrying the continuous currents and an electricexploder in shunt of the resonator, the parts being electricallyproportioned so that the continuous current periodically charges theresonator when the exploder are is not established and the resonatorperodically discharges as an alternating current through the explodcrwhen its arc is established, these alternating currents being ledthrough the primary coil of the transformer.

But in the application No. 183,247, the alternating current thus set upin the primary coil of the transformer is rectified into a continuouscurrent in the working circuit which is connected to the transformersecondary.

Now in the present application, I may utilizc the means for generating acontinuous current above referred to and I may furthermore employ themeans for converting this continuous current into an alternating ourrentin the primary circuit of a transformer as above described. But thealternating currents generated in the secondary coil of thistransformer, instead of being rectified, I now propose to supply asalternating currents of high frequency to the working circuits, and Ifurthermore propose to make both the ef fective intensity and thefrequency of these high frequency currents as constant as those ofcurrents furnished by alternators, so that one may utilize with them allthe properties of electrical resonance. To this end I have devised anexciter for thc'dynamo or prime source of current, which exciter takesits energy from the working circuit and acts in such a manner, will bemore specifically pointed out later on, that any departure from thenormal frequency of the alternating Working currents brings about such achange in theexcitation of the prime source of electrical energy as torestore this frequency to its normal value.

In the drawings,Figure 1 shows a complete diagram of my system; Fig. 2shows the electromotive-force and current curves of the prime source ofelectrical energy which I prefer to employ Fig. 3 shows another set ofcurrent curves of this prime source Fig. 4 shows the current curve ofthe apparatus which I preferlto use to transform the continuous currentsinto alternating currents; and Figs. 5, 6, 7 and 8, show types ofelectric exploders which I may employ.

In Fig. I I have indicated by I the prime source of electrical energywhich I prefer to employ and which, taken with the electrical explodersshown as spark gaps (J, 7, b, and the condenser 10, generates acontinuous current of practically constant intensity. I have designatedby II the electrical resonator and the exploder in shunt thereof, fortransforming this continuous current into alternating currents. I havefurthermore designated by III the frequency regulator which I havedevised, by means of which any departure from the normal frequency ofthe alternating working currents roduces such a change in the excitationof t is prime generator as to restore this frequency to its normalvalue. The Roman. numeral IV designates an electric valve or a symmetricdevice, used as a part of this'exciter, which has for its function topermit only currents of a given sign to pass through it and to therebyrectify the alternating exciting currents,

which are taken from the Working circuit, into the continuous currentswhich are necessary to modify the excitation of the prime generator. I

Coming now to a more specific description of the dynamo l whichgenerates an alternating electrolnotive-force having its maximum valueof one sign greater than its maxi mum value of the opposite sign, itWill be found to consist of a pair of field poles having thecircumferential extent of-the positive pole, say, much less than that ofits negative pole. The armature, in the case shown, consists of sixcoils connected in diametrically opposite pairs, and connected to therings 1, 2, 3, a, in such. amanner that the brush which rests on thering 1 acts as a common return for all the pairs of coils, and thebrushes which rest on the rings 2, 3, 4, are each respectively connectedto the other end of one of the three pairs of coils. T he armature issupposed to turn at constant velocity and to be separately excited bymeans of field coils 33, 33, in a circuit with a source of con tinuouscurrent, which impresses a constant difference of potential upon theterminals of the field coils.

It is manifest that instead of using two field poles, i may use a numberof pairs of field poles; that instead of using three pairs of armaturecoils I may use any other number of such pairs; that linay use either aseries or a p rallel connection between the coils eonstituting a pair ofcoils; and that I may connect the armature coils in sets of three ormore instcao of in pairs.

Since the circumferential extent of the positive field pole my primegenerator is less than that of the negative field pole, it follows thatthe flux intensity is much greater under the narrow pole than under thebroad pole. The armature being turned at a constant velocity within themagnetic field thus produced, it further follows that theelectrmnotive-force developed in any conductor arranged on the surfaceof the armature parallel. to the armature axis will vary as function ofthe time according to a law something like that represented by the curveA. of Fig. 2. Thatto say, the maximum value of the positiveelectromotiveforce will be much greater than the maximum value of thenegative electriimotiveforce whereas the duration of the positiveelectromotive force period will be much less than the duration of thenegative electrometive-force period.

By referring to Fig. 1, it will be seen that the electrical explodcrsi3, 7, and H, which each consist of a pair of separated balls I), areconnected to the armature circuits of ihe prime generator I so that thebulls 1, fl, are all connected through the condenser ill to side of thearmature coils by means of the common return conductor and that theballs a, a, a, by means of the brushes 2, 3 and 4, are each respectivelyconnected to the other side of the armature coils. The coin denser 10,in fact, is in shunt of the set of exploders 6, 7 and 8, and thearmature circuits of the prime generator; and each armature circuit isin series with one exploder.

Since the electric exploder or spark gap (1., 7), may be of common form,1 need only remark that in order to establish an are between suchexploders it is necessary to develop between them a voltage of a givenmagniti'ide; that the are being once established, its resistance becomesquickly negligible, and that the arc is immediately extinguished whenthe intensity of the current which traverses it is zero or becomesinferior to a certain limit.

I designate by ll the voltage necessary to establish or spring an arc inthe cxploders 6, 7, S, and by /L the voltage normally maintained betweenthe plates of the condenser 10. It is to be observed that the magnitudeof h is always less than the magnitude of H. l furthermore assume, tofix ideas, that the maximum positive value of the electrometivo-force itsupplied by any given armature circuits of the dynamo, is greater thanthe sum li+it, and that its maximum negative value is smaller than thedifference P 71.. i am, for the present, concerned merely with onearmature circuit, say that connected with the exploder 6. Since now,during the period of positive clectromotivo-force, there is available,to establish the arc in the exp loder, by reason of the presence of theconoenser 10, a voltage of 15* /t, it will be clear that some timeduring the period in which the armature coil is the seal of positiveelectromotive-force, there will be available a voltage greater than ll+/L Ii, that is to say 11, to establish this are in the exploder. .iltfollows that the exploder are will always be established some timeduring the period of positive electromotive-force in the aru'iaturecoil.

Referring now to Fig. 2, in which i: have traced a curve showing thevariation of the electromotive-force E developed between the balls ofthe exploder 6, i will assume that at the moment t,, the voltagedeveloped between. the balls of the exploder is equal lo ll,

, that is that it is at this moment sullicient to establish the are.Starting at this moment t,, the armature circuit will be traversed by acurrent, the intensity of which will gradually increase, as is shown bythe curve B in Fig. 2. if we neglect the energy lost in ihe circuits ofthe dynamo and in the cxplodcr, that is to say if we suppose negligiblethe resistance of the armature circuits and of the cxplodcr, when thelatter is in action, ihe intensity of lhe current which traverses thecxploder, omrc i1 is in action. will only be limited by the action ofthe self-induction of the armature circuit under consideratioiiv Thismeans, in effect,

lIO

that the current Bwill lag 90 degrees behind theelectromotive-force A,so that the intensity of this current B will be in maximum at the momentwhen the electromotive-force across the exploder, or theelectromotiveforce E h, is zero. All this is well shown in Fig. 2 inwhich the axis of abscissa is t. I have'furthermore traced, indots anddashes, a line'o parallel to this'axis and at a distance h above thesame. The electromotiveforce generated by the armature coil of the whichmeans that it will always prime generator is to be measured positive andnegative above and below the. axis 0 2- along the curve A. Theelectromotive-force across the terminals of the exploder 6, by reason ofthe action of the condenser 10 having a normal voltage of h, is to bemeasured positive and negative above and below the line 0 t.

Since the maximum positive electronictive-force generated by thearmature circuits is greater than H+h as before assumed, the curveA'will always have a part of its peak above the line in dashes o twhichisparallel to 0 t and at a distance Htherefrom.

Therefore, during some portion of the periodof positive electromotiveforc-e, there will always be enough potential across the ex ploder 6 toestablish an arc," as has been said efore. v

Since the maximum-negative electromotive-force generated. by thearmature circuits of the prime generator is always less than H-h, itfollows that the curve A Will never reach the line 0" t" drawn at adistance of H below the axis 0 t. This, put in other words, means thatthe maximum negative electromotive-force across the terminals of I theexploder 6, which ismeasured downward from the line 0 t, can never be eual to H,

g e insufficient to initially establish an arc across the l l l thecurrent represente have shownabove that at an epoch of r across theexploder WlllCll increases in lntensityuntil the epoch t Thereupon theinpositive electromotive-force a it, current passes tensity of thiscurrent diminishes and becomes zero. at the e ch t which epoch, accordingto the fun amental laws of current induction, is determined bythe fact that the area S shown in 'hachures is equal to the area S,shown in hachures. Itcan readily be shown that the distance t, t isalways less than the distance T between two adjacent becomes zero, thearc in this exploder will be immediately extinguished, and since, duringthe period of negative electromotive-force,

this electromotive-force never reaches a value sufiicient to initiallyestablish the are, as has been shown above, it follows that the exploderarc will not be re-established until the next positive period ofelectromotiveforce A, that is at an epoth t,+T. We see, therefore, thatthe action of the armature circuit of the prime generator which isconnected to the exploder 6 is to send into the con denser 10 a seriesof positive current waves B B,, as shown in Fig. 8, and to send intothis condenser no negative current Waves. Similarly the action of thatarmature circuit which is connected, with the exploder 7 is to send intothe condenser 10 a series of positive current waves 13,, B Finally thearmature circuit which is connected with the exploder 8 sends into thecondenser 10 a se ries of positive current waves B B B i using asufiiciently large number of dephased armature circuits on the primegenerator, it is manifest that the condenser 10 will receive what ispractically an uninterrupted charge of continuous current. The apparatuswill operate most efficiently if the voltage it, maintained across thecondenser 10, is Small with reference to the voltage H necessary toinitially establish theexploder arc.

I now come to a description of the means II for transforming thecontinuous current,

scribed, into an alternating. current of high frequency in the primarycircuit 12 of the transformer 1'3, such means consisting essentially ofan electrical resonator of a s ecified electrical design with anelectric exp oder in shunt thereof to which an automatic circuit breakermay be added for insuring the steadiness of the operation.

The primary circuit 12 ofthe transformer 13 passes through aself-induction coil 14 and a condenser 16 in series therewith. If theprimary circuit 12 has sufficient self induction in itself, the coil 14is unnecessary. Since the primary circuit 12, the self induction coil14, and the condenser 16 constitute a circuit having both capacity andself induction, they will constitute an electric res- -which is suppliedby the devices above deonator in shunt of which, as is seen, is mount edan electric exploder 17 which may also be formed of two metallic ballsa, b, separated by an air space.

. The continuous current su lied by the line 9, in the manner alreadyfil lly described passes into this resonator and charges the condenser16 for a certain time, at the end of which an arc is established in theexploder 17. This are once established, the resistance of the exploderbecomes practically zero so that we have the well .known phenomena of acharged condenser discharging through a smal external resistance. Thismeans that an oscillatory discharge will be set up giving rise to analternating current. ,The electrical constants are so chosen that beforethe end of one complete oscillation of this discharge,]

that is shortly before the end of one complete period of the alternatingcurrent set up by the discharge, the arc in the eXploder isdisestablished. The condenser 16 is thereupon a ain charged by thecontinuous current supplied by the line 9 until matters are in the samestate in which they were when the arc in the exploder was firstestablished. But matters being in. the same state in which they were atthe moment when the eXploder arc was established for the first time, itfollows that the exploder arc will be again established, that there willbe another oscillating dis charge in the condenser and anotheralternating current comprising one complete positive and one completenegative period and so on. The alternating current, thus generated, willnot gradually die down, as in the discharge of the ordinary Leyden jar,for the reason thatthe condenser is recharged from the main line at theend of each alternation.

I here remark that the self induction coil 11 helps to maintain constantthe intensity I of the continuous current in the line despite theestablishment of the eXploder arc.

It is thus seen how, by the arrangement thus far described, a continuouscurrent is transformed intoan alternating current in the primary. 12.The continuous current being of constant intensity, it can be shown thatthe alternating current into which it is transformed, is also ofeffective constant intensity.

It remains to briefly refer to the automatic circuit breaker 18. It willbe noticed that, as shown, this automatic circuit breaker consists of asolenoid in series with the primary 12 and condenser 16, there bein abranch circuit through the flexible cont uctor 155, the core of thesolenoid and the mercury circuit breaker 18 which, when the solenoid istie-energized. shorts circuits the condenser 16 and practically shortcircuits the eXploder 17. This automatic circuit breaker is designed tomaintain its core raised and the short cir cuits broken throughout thenormal opera-.

tion of the apparatus. It does not go into and out of action at eachoscillatory discharge of the exploder. But should, for any accidentalreason, such as a surcharge on the working circuits, the arc in theexploder not disestablish itself at the proper time toward the end ofany complete oscillation, the energy contained i the resonator willrapidly dissipate, so that the solenoid will permit its core to drop andshort circuit the exploder are 17. The exploder arc is therefore nowextinguished as it should be. Thereupon the solenoid again raises itscore to break the short circuits about the condenser 16 and the exploder17 so that the system may renew its normal operation. The automaticcircuit breaker has therefore the function of preventing adisarrangement of the normal operation of the system by reason of thefailure of the eX- ploder to disestablish its arc at the proper time.

I now briefly refer to the principles which are to be employed in theelectrical design of the apparatus II, by reference to Fig. 4, in whichthe axis of abscissa denotes time and the axis of ordinates denotescurrent strength or charge.

So long as the resonator is short circuited by the exploder are, it isthe seat of a current of intensity J the variation of which may berepresented by a curve resembling a sinusoid, such as the curve J shownby full lines in Fig. 4.

It is also manifest that the variation of the charge Q of the condenser16 may be represented by a sinusoid such as the curve Q in dots anddashes, in Fig. 4, this curve being dephased by 90 degrees from thecurve J.

Now it has been proposed, in the prior art, to convert a continuouscurrent into an alternating current of high frequency by charging aresonator with the continuous current and then discharging the resonatorthrough an eXploder. But such apparatus has never been perfected to apoint at which it can be commercially used and certainly not for thepurposes requiring electrical resonance, for the reason that it was notknown how to make the alternating currents of effective constantfrequency, nor how tomake them, practically speaking, sinusoidal inform. I have discovered how to do these two things. l/VithouteXplaining,-at length, how I have reacheda knowledge of the requirementsnecessary to effect these two objects, I may say that if we designate byR the ohmic resistance of the resonator, by Z the coefficient of itsapparent self induction, by c the capacity of its condenser 16, and by Ethe quantity of electrical energy stored in the resonator at any instantof time t, then the rules are these: In order that the frequency of thealternating current shall be constant, it is necessary that R shall besmall with respect to In order that the alternating current wave shallbe sinusoidal, it is necessary that the quantity of energy E stored inthe resonator shall be large with respect to that which is used up inthe system between two consecutive eX- plosions. In this connection Imay say that if E and E, are the quantities of energy stored at theinstant t in the condenser and self induction coil, respectively, and if:1; denotes the frequency we may write,

E E E,.

In order to transform the alternating currents of constant effectiveintensity in the primary circuit 12 into the alternating currents whichare to be utilized on the work- ICO 'ing circuit, 1 use the secondary 19of the transformer 13. The alternating currents in the primary circuit12 are thus transformed into alternating currents in the secondarycircuit 19 from which they are supplied to the working circuit 20. Sincethe effective intensity of the alternating current in the primarycircuit 12 is constant, the effective intensity of the secondarycurrents in the secondary circuit 19 will ordinarily be constant, thetransformer 13 being then of the constant current type and acting totransform an alternating current of constant effective intensity intoanother alternating current of constant effective intensity. If it bedesired to transform the primary current of effective constantintensityinto a secondary current of effective constant voltage, it is merelynecessary to insert a condenser in series in the secondary circuit, of acapacity to render zero the co-efficient of apparent self induction ofthe secondary.

In the above description I have assumed the power factor of the workingcircuit to be constant so that if the prime generator is regulated toproduce a continuous current of constant intensity, the frequency of thealternating currents willbe constant. I now come to a description of myregulating exciter III which is intended to regulate the eX citation ofthe prime generator I in such a manner that the frequency of thecurrents on the working circuits remains constant despite variations inthe power factor. Now an increaseyin the excitation of the field of theprime generator acts to augment the intensity of the charging current ofthe resonator in diminishing the' duration of this charge. Diminution ofthe duration of the charge will have for its effect the diminution ofthe interval of time which separates the initiation of two consecutiveestablishments 'of the arc in the exploder 17, thus augmenting thefrequency as and vice versa.

I have thus been led to rapidly augment the excitation of the generatorif the fIGC uency diminishes and to rapidly diminish t is excitation ifthe frequency increases. In this way I bring about theresult that thefrequency on the working circuit/does not vary except between limits asclose together as I please.

Let us assume that the working circuit is the ordinary series circuittraversed by a current of effective constant intensity. Intercalate inseries in this circuit, the primaries 21 and 22 of two transformershaving secondary circuits 23 and 24. But if the working circuit 20 is ofthe multiple arc type, supplied with current at constant voltage, theprimary circuits21 and 22 will be mounted in multiple therein. Butwhether the worl ing circuitis of the series or the multiple arc type, Imount a primary circuit 26 of a transformer-200 and a condenser 25 inseries with the secondary circuit 23 and I furthermore mount the primarycircuit 28 of another transformer 300 and a condenser 27 in series withthe secondary circuit 24.

The secondary circuits 29 and 30 of the transformer 200 are wound inopposite directions so that each has the same co-eificient of selfinduction but so that the co-efflcientsof mutual induction with theirprimary circuit 26 are equal and of opposite signs. A similar remarkapplies to the secondary circuits 31 and 32 of the transformer 300.

I designate by y a frequency which is small with respect to thefrequency as. I furthermore determine the capacity of the condenser 25in such a manner that the apparent self induction of the circuit 23, 25,26, is zero when it is traversed by currents of frequency awy. Ifurthermore determine the capacity of the condenser 27 in such a mannerthat the apparent self induction of the circuit 24;, 27, 28, is zerowhen it is traversed by a current of frequency a: y. From this itfollows that the electromotive-force developed in the secondary circuits29, 30 and 31, 32, will be equal when their frequency is in. When thefrequency of the current in the working circuit diminishes and fallsbelow r and thereby gets nearer to m-y and farther from ac+' 1 theelectromotive-force developed in the circuits 29, 30,will increase, andthe electromotive-force developed'in the circuits 3], 32, will diminish.On the other hand, when the frequency of the alternating current in theworking circuit increases above 00, and gets nearer to and farther awayfrom as 3 the electromotive-force in the secondaries 31, 32, willincrease and that in the secondaries 29, 30, will decrease.

The prime generator I has exciting field coils 33, 33, interconnected inany suitable manner and traversed by a continuous current furnished. byany local source of electrical energy, which maintains a constantdifference of potential between the conductors 36 and 37. This is acommon way ofexciting the field magnets of a generator, and I needonly'say that I regulate the intensity of this local source of currentin such a manner as to normally excite the prime'generator to furnish tothe working circuits currents of frequency .16 at mean'load.

The coils 34, 34, which are connected to the secondaries 29, 30, arewoundv in such a way as to re-inforce the magnetizing effect of thefield coils 33, 33. On the other hand the field coils 35, 35, which areconnected to the secondaries 31, 32, are wound to counteract themagnetizin effect of thefield coil 33, 33.

Not undertaiing to explain,'for the moment, the particular way ofcompleting the connection of the secondaries 29, 30, with the fieldcoils 34, and of the secondaries 31, 32, with the field coil 35, it willnow at once be apparent that should, for any reason, the

frequency of the alternating current on the working circuit 20 increaseabove the normal frequency as, the electromotiveforce, in thesecondaries of the transformer 300 will increase, which means that therewill be more current in the field coils 35', subtracting from the effectof the exciting coil 33. At the same time the electromotive-force in thesecondaries of the transformer 200 will de crease, so that there will beless current in the field coils 34, to re-iniorce the normal fieldexcitation of the coils 33. Both these actions, then, combine todecrease the excitation of the prime generator I, which means, as hasbefore been explained, that the frequency of the alternating currentsgenerated in the working circuit 20 will be decreased to restore thenormal frequency. A corresp onding remark applies if the frequency ofthe alternating working currents should, for any reason, fall belownormal.

The connection between the secondaries of the transformer 200 and thefield coils 34 as well as between the secondaries of the transformer 300and the field coils 35, are completed through the electric valve orasymmetric device IV in a manner which will be apparent from a study ofthe drawing. One end of the secondary 29 is connected to the electrode40. The corresponding end of the secondary 30 is connected to theelectrode 39. One end of the secondary 31 is connected to the electrode43 and the correspond,- ing end of the secondary 32 is connected to theelectrode 44. Opposite these electrodes just mentioned and co-operatingwith each of them is the electrode 400, which is connected to the wire37 and thereby to one terminal of each of the field coils 34, 35. Theother terminals of the field coils 34, 35, are connected, respectively,to the secondaries 29, 30, and 31, 32, by means of conductors 38 and 42.A circuit is thus established from the secondaries 29, 30, to theelectrodes 39, 40, and across the vacuum to thecommon terminal 400,thence to the conductor 37, through the field coil 34, the wire 38, andback to the secondaries 29 and 30. A similar circuit may readily betraced connecting the secondaries 31, 32, through the electrode 43, 44,and the common terminal 400, with the field coil 35. l

The electric valve TV which I have shown comprises terminals 39, 40, 43,44, which are composed of bells of steel or iron, of one sign, locatedin a vacuum tube and a terminal 400, of opposite sign, composed of adrop of mercury. Such a construction has the remarkable property thatonce an arc is established in the vacuum tube, it will permit thecurrent to pass from the steel bell to the mer- ,cury but will oppose apractically infinite resistance to the current passing in the oppositedirections from the mercury to the steel bell. I may say immediately,however, that although this construction is Very efiicient forrectifying alternating currents, it is only here given by wayol example.Explaining the action of this electric valve a little more fully, it isto be noted that an alternating current traversing the primary circuit26 of the transformer 200 generates, say, a positive wave ofelectro'motivedorce in the secondary 29 and a simultaneous negative waveof electromotive-force in the secondary 30, this being due tothe factthat these secondaries are oppositely wound. An are being assumed asestablished in the electric valve, we will suppose that the connectionsare so fixed that the positive electromotive wave is allowedto generatea current passing from the electrode 40 to the electrode 400. At thistime, the negative wave of eletromotiveforce in the secondary 30produces no effect. But in the next half period of alternating currentin the primary 26, there will be a negative wave of electromotive-forcein the secondary 29, and a positive wave of electromotive-force in thesecondary 30 so that a current now passes from the electrode 39 to theterminal 400, and no current passes from the terminal 40 to the terminal400. This means that there will always be a current in a given directioncirculating through the coil 34, passing in one half period from 39 to400, and in the next half period from 40 to 400. The oppositely woundsecondaries 29, 30, taken together with the terminals 39, 40, and thecommon terminal 400, of the electric valve have caused a rectifiedcurrent to pass through the field coil 34, such rectified current beingnecessary for the proper differential excitations of the rims generator.A similar remark manifest y applies to the field coil 35, thesecondaries 31, 32, the ter' minals 43, 44, and the co-operatingterminal 400.

While it is true that, the are once established in the electrical valveIV, the gap between the terminals 39, 40, 43, 44, and the co-operatingterminal 400, offers a practical negligible resistance to currentsflowing in a given direction and prevents the fiow of currents in theopposite direction, it is yet neces sary, in order to initiallyestablish the arc, to impress a high voltage across the terminals. Tothis end I add a fifth electrode 45, of iron or steel, to the electricvalve, and place it in circuit withthe impedance coil 46which isthereupon connected with the conductor 36. I also run a ta through theresistance 47 and the circuit reaker 48, to the conductor 37, in themanner shown. By closing the circuit breaker 48, a current is passedthrough the impedance coil 46. When the circuit breaker is opened, theimpedance coil 46 gives off a high tension discharge in a circuit whichcontains the field coil 33, which jumps from the terminal 45 to theterminal-400 and initially establishes the arc in the electric merelydescribed what may be called generic types of electric explodersandelectric valves,

and that I may use other types.

In order to insure the instantaneous extinction of the arc in suchexploders when the current traversing them becomes zero, I may send acurrent of air between the balls a, b, as indicated in Fig. 5. Or I mayreplace the balls by two-horn shaped parts a, b,

situated between the polar extremities of an electro magnet, asindicated in Fig. 6. Again I may inclose theballs a, b, in a vacuum tubeas shown in Fig. 7, such eX- ploders going out of action instantaneouslyas soon as the intensity of the current traversing them sinks below acertain limit. ()ne of the most efi ective forms of electric exploderwhich may be employed consists of an inverted U tube inwhich a vacuum ismaintained, the terminals being constituted by globules of mercury inthe inverted ends of the tube, all as shown in Fig. 7. The effectiveresistance of such tubes is very small, 'after the arc has once beenestab-.

lished; they go out of action instantaneously and the surface of theirelectrodes is not injuriously effected.

This is a division of my application N 0. 192,227, filed Feb. 5, 1904,in which the process is claimed.

I have not claimed herein the automatic circuit breaker nor certaindetails of my electric valve since these are covered in my companionapplication filed Nov. 30, 1903, under SerialNo. 183,247.

I claim,

1. A system for transforming unidirectional currents into alternatingcurrents of constant frequency comprising a line carrying continuouscurrents, a resonator having R small with respect to an induction coilhaving its primary connected with the resonator, and an electricexploder in shunt of the resonator, substantially as described.

2. A system for transforming unidirectional currents into alternatingcurrents which are sinusoidal in form, comprising a line carryingcontinuous currents, a resonator arranged to store an amount of energywhich is large with respect to that consumed in an alternating period,an induction coil having its primary connected with the resonator, andan electric ex loder in shunt of the resonator, substantially asdescribed.

3. A system for transforming unidirectional currents into sinusoidalcurrents, of

constant frequency, comprising a line carrymg continuous currents, aresonator having R small with respect to 4:] and arranged to store anamount of energy which is large with respect to that consumed in analternating period, an induction coil having its primary connected withthe resonator, and an electric exploder in shunt of the resonator,substantially as described.

4. A prime generator of unidirectional current and an exciter windingtherefor, a circuit carrying alternating currents transformed from theunidirectional currents, and an electrically tuned circuit associatedwith this circuit and with the exciter winding to maintain the frequencyof the alternating currents constant, substantially as described.

5. A prime generator of unidirectional currents, and an eXciter windingtherefor, a circuit carrying alternating currents trans formed from theunidirectional currents, and an electrically tuned circuit and anelectric valve or current rectifier, associated with the alternatingcurrent circuit and the exciter winding to maintain the frequency of thealternating current constant, substantially as described.

6. A prime generator of unidirectional currents and a pair ofdifferential exciter windings therefor, a circuit carrying alternatingcurrents of a normal frequency transformed from the undirectionalcurrents, and circuits electrically tuned to a frequency respectivelyabove and below normal associated, on the one hand, with the alternatingcurrent circuit, and, on the other hand, with the differential exciterwindings respectively, substantially as described.

7. A prime generator of unidirectional currents and a pair ofdifferential exciter" windings therefor, a circuit carrying alternatingcurrents of a normal frequency transformed from the unidirectionalcurrents, circuits electrically tuned to a frequency respectively aboveand below normal, and electrical valves or current rectifiers eachrespectively connected to a tuned circuit and an exciter winding,substantially as described.

8. A prime generator of unidirectional current and an exciter windingtherefor, an electric resonator and an exploder in shunt thereof fortransforming the unidirectional current into alternating currents, andan electrically tuned circuit energized by these alternating currentsand associated with the exciter winding to maintain the alternatingcurrents of normal frequency, substantially as described.

9. A prime generator of unidirectional current and a pair ofdifferential exciter windings therefor, an electric resonator and anexploder in sh mt thereof for transforming the unidirectio al currentinto alternating currents, and a pair of circuits energized by thesealternating currents, tuned to a frequency respectively above and belowthe normal frequency it is desired to maintain, and in turn energizingthe exciter windings of the prime generator to maintain the normalfrequency UOIIStEHlt, substantially as de scribed.

10. A prime generator of unidirectional current and a pair ofdifierential exciter windings therefor, an electric resonator and anexploder in shunt thereof for transforming the unidirectional currentinto alternating currents, a pair of circuits energized by thesealternating currents and tuned to a frequency respectively above andbelow the normal frequency it is desired to maintain, and electricvalves or current rectifiers connected to a tuned circuit and an exciterWinding respectively, substantially as described.

in testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

MAURICE LEBLANC. Witnesses PIERRE LAVAUX, I'IANSON C. CQXE.

